1. Field of the Invention
The present invention relates to a manufacturing method of a package which can seal an electronic part in a cavity.
2. Description of the Related Art
Recently, a package product having the following constitution has been popularly used. The package product includes a base substrate and a lid substrate which are bonded to each other by anodic bonding in a laminated state so as to form a cavity therebetween, and an operating piece which is mounted on a portion of the base substrate positioned inside the cavity.
As this type of package product, for example, there has been known a piezoelectric vibrator which is mounted on a mobile phone or a personal digital assist and makes use of crystal or the like as a time source, a timing source for a control signal or the like, a reference signal source or the like.
Also, there has been known a method where such a package product is formed as follows (see JP-A-2006-339896).
Firstly, a base substrate forming wafer and a lid substrate forming wafer are set in an anodic bonding device arranged in a vacuum chamber, and these base substrate forming wafer and lid substrate forming wafer are overlapped to each other by way of a bonding film for anodic bonding which is made of a conductive material.
On a bonding surface of the lid substrate forming wafer, a plurality of recessed portions which form cavities when the lid substrate forming wafer overlaps the base substrate forming wafer are formed.
On a bonding surface of the base substrate forming wafer, a plurality of operating pieces are mounted corresponding to the plurality of recessed portions formed on the lid substrate forming wafer, and a bonding film is formed on a portion of the bonding surface except for portions where the operating pieces are mounted.
Then, the lid substrate forming wafer is set on an electrode plate of the anodic bonding device.
Next, while activating ions in the lid substrate forming wafer by heating the lid substrate forming wafer, a voltage is applied between the bonding film of the base substrate forming wafer and the electrode plate thus supplying an electric current to the lid substrate forming wafer.
Accordingly, an electrochemical reaction is generated on an interface between the bonding film and a bonding surface of the lid substrate forming wafer so that the bonding film of the base substrate forming wafer and the lid substrate forming wafer are bonded to each other by anodic bonding thus forming a wafer bonded body.
Thereafter, a plurality of package products are formed by cutting the wafer bonded body at predetermined positions.